Astra Mk4 1.6 16V Sport (Ecotech) engine q's:

Long story short: just been to see a favourably priced '99 Astra 1.6 Sport (16V Ecotech engine). The lad said the cambelt tensioners went 'about 10,000' miles ago so he had the head rebuilt and new headgasket. He's not used the car in a few months and it hasn't been used he tells me. Anyhow went to see it today, he fired it up and it sounds and drives well enough BUT...it's smoking a bit when revved hard and also when first started. Very slight 'mayo' signs on the bottom of the filler cap, being fair I expect this could be condensation after it stood a while. The smoking got me thinking though, he says once warmed up it's fine as he'd left a couple of months before and it did it until a good couple of hours welting it cleared the smoke. Although he'd done an oil and filter when he rebuilt the head I wondered if fresh fuel, oil/filer change and some Redex injection treatment (or similar) would help or whether I should be worried about the smoke?
Water looks slightly dirty but not enough to worry me by the way and the oil didn't look like it showed any hadgasket failure signs after a test drive. He'd let the car warm up on his drive before I get there and I went about 2 miles in without thrashing it too hard and it reached mid-temp and the fan cut in so don't see a problem on that score.
Any thoughts greatly appreciated because while the price is right I don't really want to be lobbing loads of money at it once I've bought it. It's got a few months test still left to run by the way.
Thanks in advance, hope the above made sense.

White-ish with the ooccasional dark bit if that makes any sense? I do know the lad he works in my local garage and rebuilt the head there, aside from the skimming which he had done at an engine reconditioner's place apparantly. He is only young and Christ knows how he could afford to insure it but most of his story does make sense and I have a very suspicious mind when it comes to people selling cars.

Edit: he had to jump start it as the battery was flat and it's my fault for not turning up first without phoning as I'd have liked to have seen it and heard it start from cold. No apparant engine noises at all though, did some quite rigourous tests on that including booting it in 5th from about ten mph onwards to try and catch any signs of rattles or knocks.

White smoke may just be condesation out of the exhaust system, especially if its been sitting a while.
Or it could be headgasket failing, you'd expect it to overheat tho.
Does it clear after its been run for a while?

I've not had the chance to give it a really good run out yet tbh. We got the engine warm from idle and a 2 miles ish blast but we didn't go mad though the fan cut in and the car reached normal temp. I'm thinking that *maybe* a really good thrashing after an oil/filter change, some fresh fuel and some Redex will do the job.

Cheers smokey. I didn't think a thrashing would stop it burning oil but had hoped that if it is condensation it would clear up. I don't see the point in using oil and fuel addatives if there is an engine problem because it's a temporary fix and not a cure. Might have another look at it again later and see if I can video the smoke and post it up on here. As I say when it first starts after knocking the engine off it smokes (which makes me think valve stem oil seals) and then when ticking over I can't remember seeing any smoke until it's revved when there is a fair amount.
If it gets any cheaper though (which I'm hoping it will) then I'd be daft not to buy it.
Thanks for the advice by the way, grateful for some more thoughts on this.

it likely is the stem seals. but he said the belt fuked up and he had to do the head.. either he didnt change the stem seals or the valves r fuked.
not someone id want to buy a car off unless it was super cheap, like &#163;50

Oddly enough I've been talking to him about it just a few minutes ago and the bloke who own the garage. Seems the bores looked fine when he repaired the car and the valve stem oil seals etc were all done at the time but the garage owner tinks it's using oil and shouldn't be smoking like that, says he thinks it might need new rings as the rest of the engine is fine. It's still very cheap for what it is and it's just come down even further in price. I'm in two minds with it really, it's cheap enough to buy it, give it an oil and filter change, some new fuel a bit of fuel and oil addative and a good pasting to see if it clears but being honest I don't think it'll clear it completely, though if I can use it for a few months there's still enough profit to be made selling it as it is and advertised with known fault(s).

Right: quick update: it's been fine recently with no signs of any smoke at all. Until yesterday when I had it ticking over for about 25 minutes. The fan kicked in and it was ticking over fine. Then, when I went to pull away, it was smoking again until driving for about 3 miles and it cleared again. This leaves me to think whatever is causing it doesn't happen until the engine is hot (as opposed to just 'warm' after a good run when the fresh air has hit it). So, assuming that, what could cause it to smoke only when engine is hot please?
I should add that wehn it is smoking there is no noticeable lack of power or anything.